When 76-year-old Hattie Wiener had a hip replacement last year, the first thing she asked her doctor was how soon she could have sex.

Next, she asked when she would be able to play with her grandchildren.

Sex is very important to Hattie. It is one of the reasons, but not the only reason, she just dates men under age 35.

“I’m a snob about people’s bodies if I’m going to bed with them,” she tells The Post. “I know my own body, I know what turns me on.”

Hattie is one of the women featured in “Extreme Cougar Wives,” premiering Nov. 25 on TLC, the channel that specializes in showing alternative lifestyles in shows like “My Big Fat Gypsy Wedding” and “Sister Wives.”

On the show, Hattie is seen on a blind date with a 29-year-old guy and, later, picking up a 25-year-old at a Midtown hotel swimming pool.

The mother of two and grandmother of three grew up in a housing project in Williamsburg, Brooklyn and now lives in a Hell’s Kitchen studio, where the walls are covered with mirrors and glamour shots of herself.

The youngest man she has had sex with was 18 — which she says was recently. She has never gone to bed with anyone over 52.

Her fondness for young men, she says, began after her divorce.

“When I was 53, 54, I was a walking ‘Yes,’ honey!” she says with a booming laugh. “I’d walk by a department store and say to a young guy, ‘Man, those shoes are gorgeous,’ and he’d say, ‘You’re gorgeous!’ ”

The former dancer and movement therapist says she still sees herself getting married again — this time with one of her young conquests.

“It would be great if my next husband was 35 or so; then he could go on after my death and still have kids.”

She has done the math. Hattie plans on living another 20 years, and marrying a man that young means she’ll never have to be with “an old man” again.

Hattie meets many of her partners on the dating site OKcupid.com. She admits that she lists her age as 66 in her bio to sneak into a younger age bracket, but she always tells men who message her that she is actually 76.

She gets messages from men as young as 19 and 20 every day, she claims.

Both of her children accept her lifestyle, she says, although her son was slower to come around. “It’s different for boys,” she says.

“I have never come on to his friends, though.”

Hattie says she has never had plastic surgery and won’t dye her bright-white hair because, “When I’m making love, I like to be naked in mind, body and spirit. I don’t want roots in my hair or scars on my face.”

The older she gets, the more beautiful Hattie feels. She stays youthful by maintaining a holistic diet, swimming and, once a day, she defies gravity on a work-out contraption that flips her upside down.